Jaming and Geometry of Two-Dimensional Foams

TL;DR

This study experimentally investigates the jamming transition in 2D foam packings, analyzing geometrical and force distributions near the critical density, and confirms theoretical scaling predictions.

Contribution

It provides experimental validation of scaling laws and force distributions in 2D foam jamming, extending understanding of the geometrical and force network behavior.

Findings

Confirmed the scaling of average contact number with density.

Distribution of areas depends strongly on density.

Contact force distribution varies systematically with density.

Abstract

We experimentally probe the vicinity of the jamming point J, located at a density $\phi$ corresponding to random close packing ($\phi_{rcp} = 0.842$), in two dimensional, bidisperse packings of foam bubbles. We vary the density of the foam layer and extract geometrical measures by image analysis. We confirm the predicted scaling of the average contact number Z with $\phi$ and compare the distribution of local contact numbers to a simple model. We further establish that the distribution of areas $p(A)$ strongly depends on $\phi$. Finally, we find that the distribution of contact forces $p(f)$ systematically varies with density.